Power transmission



June 28, 1938- j "a i. Rosa :r AL 2,122,045

' v Pomgv TRANSMISSION Filed ont.v 22, 1935 INI/E N TORS) l ATTORNEY Patented'June 28, 1938 I m TRANSMISSION. Eclwinl..Rmocanclllalpllli.Timeline,Waterassis-nora bury, Conn.,

Company, Waterbury, Conn., a annotation of Connecticut Application om zz, lass, seran No. 40,14:

1s claim. (ctn-ss) 'Ihis invention relates to power transmissions of the. type which include one or more energy translating devices for converting mechanical motion to movement of a fluid under pressure or s vice versa. Transmissions of this class usually 'comprise a fluid pump connected in a closed circuit with a i'iuid motor. In apparatus of this .type which operates upon a substantially incompressible fluid, it is important to insure that l the fluid circuit isv maintained full of liquid at all times. It has also been found necessary partic ularly where a variable displacement pump or motor is in the circuit to prevent the building up of excessively high pressures in the cirl cuit under abnormal operating conditions.

In a iiuid power transmission of the type illustratsd in Patent to Janney, 924,787, for example; in which the fluid pump is variable in displacement and is also reversible in the sense that the direction of fluid ow may be reversed without reversing the direction of motion of the operating shaft, it has heretofore been customary to provide duplicate replenishing valves las well as duplicate relief valves to accomplish these purposes. These valves are usually mounted in bores formed in a-part of the casing ofthe transmission and constructions heretofore utilized have necessitated not only a large number of bores and connecting passages' but also unnecessary $0 duplication of the valves themselves, resulting in undesirably high cost of the apparatus.

It is an object of the present invention, therefore, to provide a single unitary valve structure .which may be incorporated in a reversible flow fluid powertransmission which will insure the proper replenishment of leakage iluid and also prevent excess pressure regardless of the direc-` tion of iluid flow within the transmission.

Itis also an object to provide a shuttle type' 0 replenishing valve for a reversible iiow fluid power transmission, which is positively maintained in operative position during normal'operation and is also positively operable to reverse the I connections for replenishing upon reversal of the 4l direction of i'luid flow.

i A further object is to provide relief valve means which permit the luse of a very light and inexpensive vspring for maintaining the valve closed.

u It is also an object'to provide a relief valve lo mechanism for a reversible iiow uid power transmission in which a single spring takes care of the relief ofexcess, pressure regardless of the direction of fluid ilow in th transmission.

Further objects and advantages of the present gg invention will be apparent from the following description, reference being had to the accompanying drawing wherein a preferred form o the present invention is clearly shown. v

In the drawing:

Figure 1 is a side elevation partly in section I of a valve plate constructed according to the present invention.

Figure 2 is a fragmentary cross-sectional view of Figure l. showing the parts in a different position. l0`

Figure 3 is a cross-sectional view taken on line 3 2 of Figure 2.

Figui-e4. is a cross-sectional view taken on line 4-4 of Figure 2.

Referring now to Figure l, there is illustrated l5 a valve plate i0 which may be associated with a fluid power transmission of the well-known Waterbury type, such as illustrated in the Janney patent referred to. Valve plate I 0 is adapt-v ed to form an operating partition between the 20 pump and motor casings of the power transmission or it may form alternatively an end closure for the casing of either, where'the pump and motor are spaced from each other and connected by piping. The; valve plate IB cooper- 25 ates with the cylinder valve to form respectively transposable high side and low side passages I 2 and i4. The passages I2 )and I4 together with the pump and motor forni a closed uid circuit.

For the purposes of the present invention the 30 valve plate Il is provided with a transverse bore 'l having enlarged portions Il .and 20 at its opposite ends. The enlarged portion i8 is in communication with the passage I2 through a conduit 22 while a similar conduit 24 connectsv 35 the enlarged portion 20 with the passage I4. vThe conduits 22 and 24 may be formed by drilling from the outside of the valve plate, the outer ends being closed with plugs 28 and 28. The midportionof the bore il communicates with asource 40 of replenishing fluid through a passage or conduit formed by'a vplurality of drill holes l0 (see Figure'4), the holes 20 being closed at their outer ends by plugs 32. A bore I4 connects the lower ends of the holes Il and is in communication with a source of replenishing fluids; for example. the idle iiuid maintained within the casing of either the fluid motor or the fluid pump or both. Slidably mounted within the bore i6 is a shuttle valve unit I4. The valve unit 38 in- 50 cludes a central longitudinal stem 38 of generallytriangular cross section having .cylindrical portions 4l upon which are slidably mounted a pair of hollow cylindrical sleeves 42 and 44 which form piston-like portions on thevalve unit 36. The sleeves 42 and 44 engage the walls of the bore I6 with a freely slidable but substantially fluid tight t.,f

VAt either end of the stem 88 there is securely fastened thereto one of a pair of plugs or heads 46 and 48 adapted to coact with the outer end of the sleeves 42 and 44 to provide a iluid tight en closure for the same. A spring 66 surrounds the stem 38 between the'sleeves 42 and 44 to urge the sleeves outwardly to fluid tight engagement with the heads' 46 and 48. Adjustment washers 52 may be provided when the valve unit is assembled and may be replaced with washers of different thickness for adjustment of the spring pressure exerted on the sleeves 42 and".

The enlarged portions I8 and 26 of the bore I6 are closed at their outer ends by screw threaded closure members 54 and 56. The closure members 54 and 56 have integral tubular extensions 56 and 66 respectively which have an internal crosssection corresponding to and in alignmentwith the bore I6. Slots 62 and 64 are formed in the tubular extensions to terminate short ofy the end ofthe extensions for a purpose later to be described. Within each of the extensions 58 and 66 there is mounted one of a pair of light valve centering 4springs 66 and 66 which are slightly pre-stressed in their extended position by :a pair of retainingmembers 'I6 and 12. The retaining members are provided with lugs 'I4 and 'I6 'which extend into the slots 62 and 64 respectively, thus limiting the expansion of the springs 66 and 68.

The tubular extensions 68 and 66 form guide means for the sleeves 42 and 44 which are necessary to maintain alignment whenever the shuttle valve unit is moved to a position in which either sleeve lies entirely outside of the bore I6.

In operation of the device whenever the fluid pump of the power transmission is idle or is operating at zero displacement so vthat o duid is being pumped, the pressures in the passages I2 and I4 will be substantially equal. Under these conditions the valve unit 86 is maintained in the neutral position illustrated in Figure 2 by the force of the springs 66 and 66 acting through the retainer 'members 16 and 12 upon the heads 46 and 46. Whenever the pump is in operation and the displacement thereof and the load on the power transmission are such that pressure is built up in the passage I4, the passage I2 may be referred to as the low side of the transmission and the passage I las the high side of the transmission.v Under'these conditions the pressure within the enlarged portion 26 predominates to overcome the force of the spring 66 and move the valve unit 36 as a whole to the right as illustrated in Figure 1. The movement of the valve unit in this direction is limited by a stop I8 formed on the closure member 64. The axial dimensions of the bore I6 and the sleeves 42 and 44 are so chosen that with the valve unit 36 against the stop .18, the sleeve 42A is entirely out of the bore I6, while the sleeve 44 moves' up to the edge of thel conduit formed by the drill holes 66. With the valve in this position a substantially' unrestricted path for replenishing iiuid isopen. This path comprises the bore 34, the drill holes 66, the bore I6, the enlarged portion I8 and the conduit 22 to the low sidel passage I2. The springs 66 ltially 'over the drill holes 36.

aisaoss axial force of the. uid pressure within the enlarged portion 26 receives a force sufoient to compress the spring 56 and permit the sleeve 44 to move to the right relative to the 'remainder of the valve unit 36. A relief path is thus opened from the passage I4 directly to the passage I2 through the conduit 24, the enlarged portion 26, the space between the head 46 and the'sleeve 44,

the passages between the sleeve 44 and the stem 38,the bore I6, the enlarged portion I8 and conduit 22. Thus, the uid circuit is effectively shunted or by-passed until .suilicient iuidk has been relieved to permit the pressure to drop to normal operating value when the sleeve 44 takes up its normal position under the iniluence o spring 56.

It will be noted that the area of the sleeve 44 exposed to axial pressure forces is small so that a comparatively light spring 56 may be used to maintain the sleeve 44 against the head 48 at high operating pressures. This annular area may be made substantially no'greater than the area of opening between the end of the sleeve 44 and the head 48. In addition, the shape of the head 48 and the coacting portion of the sleeve 44 is such that as soon as the relief valve formed thereby opens, a larger net annular area of the sleeve .44 is exposed thus further opening the relief valve.

When the sleeve 44 moves to the right to open the relief valve, the right hand end thereof moves across the passage or conduit formed by the drill holes 36 to cut oiT the bore I6 andthe rest of the normal replenishing path from the source of replenishing iluid, thus effectively preventing the exhaustion of relieved uid tothe replenishing source. In addition, the sleeves 42 and 44 may be beveled'as shown at 62 for the purpose ofl causing a Venturi effect while the sleeve 44 is only par- Thus with the sleeve 44 moved to the right so that the bevel 'portion 82 does not completely close the holes 86,

the relieved fluid passing through the interior of sleeve 44 leaves the right-hand end thereof at a high velocity. Upon entering the bore I6 its velocity is reduced so that at the holes 36 the bevel 82 induces a suction 'effect tending to draw fluid from the holes 36 along with the major current flowing through vthe interior of sleeve 44.I Upon operation' of the transmission in the reverse direction the passages I 2 and I4 are transposed in respect to the high and low pressures so that the passage I2 is on the high side and the passage I4 is on the low side. The valve unit 36 operates in an exactly analogous manner to open a replenishing path from the bore 34 to the passage I4, stop means 86 similar to I8 being provided on member 56 and upon excess pressure A being developed in the passage I2 opens a relief lpath directly from passage I2 to passage I4.

Whenever the pressure conditions in the uid circuit go through a neutral point in changing from one Ycondition to another, either the spring- It will thus be seen that the present invention provides Aa unitary valve structure for a reversible lflow fluid power transmission which is not only simple and economical to construct but is positive in its operation under all conditions encountered in use.

V .While the form of embodiment of the invention as herein disclosed, vconstitutes a preferred form. it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

l. In combination with a uid pressure energy translating device having a pair of iluid passages with respect to which the high and low pressure sides of the device are transposable, a combined replenishing and relief valve comprising means defining a valve bore, means forming a conduit communicating between said bore and a source of replenishing fluid, conduit means connecting the bore at spaced points with each of said uid passages, a valve unit reciprocable in the bore and having portions oppositely exposed to the pressure in said uid passages and operable in response to pressure in either of said passages to open the other passage to the replenishing source, and means responsive to excessive pressure for causing said valve unit to open communication between the passage which is under pressure and a point oflowfpressure.

2. In combination with a fluid pressure energy translating device having a pair of uid passages with respect to which the high and low pressure sides of the device are transposable, a combined replenishing vand relief valve 'comprising means deilning a valve'bore,means 4forming a conduit communicating between said bore and a Asource of replenishing fluid, conduit means connecting the bore at'spaced points with each of said iluid passages, a valve unit reciprocable in the bore and having portions oppositely exposed to the pressure in said fluid passages and operable in response to pressure in either of said passages to open the'other passage to the replenishing source, and means responsive to excessive pressure for causing -said valve unit to open communication between the passage which is under pressure and the other passage through said bore..

3.` In combination with a iluid pressure energy translating device having a pair of fluid passages with respect to which the high and low pressure sides of.the device are transposable, a combined replenishing and ,relief valve comprising means defining a valve bore, means forming a conduit' communicating between said bore and ta source of replenishing iiuid, conduit means connecting the bore at spaced points with enen of .said'auid ges, a valve unit reciprocable in the boreV and yhaving portions `oppositely exposedto the pressure in said iiuid passages and operable in response to pressure in either of said passages to open the other passage to the replenishingsource, and means responsive to excessive pressure for causing said valve unit to open communication between the passage which is under pressure and the other passage through said bore' and to in'- terrupt communication between said other passage and the replenishing source.v

4. In a pressure fluid circuit having a pair of passages which may be interchangeably subjected respectively to high and low pressure fluid the combination of means deiining a single valve borehavingcommunication at spaced points with 'each of said passages and with va. source of replenishing i'luid. and a single valve unit reciprocable in said bore operable in response to uid pressure toconnect the replenishingsource'witirthepas-v operating pressure.

sage which is exposed to low pressure and to limit the pressure developed in the high pressure j passage to a predetermined maximum value.

5.` In a pressure iluid circuit having a pair of passages which may be interchangeably subjected respectively to high and low pressure iluid the combination of -a bore having communicationA with each of said passages at opposite respective l ends of the bore and with a third passage at an intermediate point. a shuttlevalve unit reciprocable in the bore to place the third passage in communication with either one of the iii-st mentioned passages in response to iiuid pressure in the other one, and means for moving the valve unit to a neutral position'closing of! communication of the third passage with both of the first mentioned passages when both passages lack operating pressure.

6. In a pressure iiuid circuit having a pair of passages which may be interchangeably subjected respectively to high and low pressure iluid the combination of a bore having communication with each of said passages at opposite respective ends of the bore and with a third passage at an intermediate point, a shuttle valve unit reciprocable in the bore to place the third passage in communication with either one of the ilrst mentioned passages in response to iluid pressure in the other one, and resilient means for moving the valve unit to a'neutral position from either operating position, for closing oi! communication of the third e with both of the ilrst mentioned passages when bothpassages lack 7. In a pressure uid circuit having a pail` of passageswhich may be interchangeably subjected respectively to high and low pressure fluid the combination of -a bore having communication with each of said passages at opposite respective ends of the bore and with a third passage at an .intermediate point, a shuttle valve unit reciprocable in the bore to place the third passage in communication with either one ofthe nrst mentioned passages in responseto iluid pressurein the other one, and resilient meansvfor-'moving the valve unit to a neutral position from either operating position, for closing oi! communication of` the third passage with both of the iirst menf tioned passages when both passages lack operat-l ing pressure and means for prestressing said resllient means at neutral position.

8. In a iluid power transmission device the combination of means for converting energy between a moving member and a body of uid under pressure at varying i'luid pressures, respectively transposable high sidel and low side duid passages for said means, a shuttle valve for selectively connecting a source of replenishing iluid with-whichever of the passages 'is on the low side at any time, and means associated with the shuttle valve for relieving excess pressure in whichever passage is on the high side. r

9. In a duid power transmission device the combination of means for converting energy becombinationof means for energy be tween a moving member and a body'oi iiuid under pressure at varying uid pressures, respectively transposable high side and low side iluid passages for said means, a single valve bore communication at its opposite ends with each of said'passages respectively, valve means in said' ing fluid, a valve member slidable in the bore having two spaced piston-like portions exposed to the opposite ends oi the bore, said portions being spaced to close communication between the replenishing iluid source and both of the passages in one position of the valve and to provide unrestricted communication between the replenishing uid source and the low side 'passage in av second position of the valve, and resilient means urging the valve into the ilrst position, the porltion exposed to the pressure of the high side passage serving as a piston to move the valve into the second position.

12. In a uid pressure circuit having a pair of passages which may be interchangeably subjected respectively to high and low pressure iluid the combination of means forming a. bore having communication at its opposite ends with each ot the passages respectively and at an lintermetiliate point communicating with a source of replenishing fluid, a valve member slidable in the bore having two lspaced piston-like portions exposed Yto the opposite ends of the bore, said portions being spaced to close communication between the replenishing uid source and both of the passages in one position oi the valve and to provide unrestricted communication between the replenishing fluid source and the low side passage in` a second position of the valve, and resilient means urging the valve into the ilrst position, the portion exposed to .the pressure of the high side passage serving as a piston to move the valve into the second position, and means i'or guiding the valve member when one of the portions is out of the bore.

13. A fluid power transmission comprising in combination a. 'uid pressure ,energy translating device having a pair of iluld passages with respect to which the high and low pressure s idies of the device are transposable, a combined reupon an abnormal pressure rise in the high pressure side. v f

14. .A fluid power transmission comprising in combination a reversible and selectively variable iiuid displacement device including a valve plate having a pair of fluid passages with respect to lwhich the high and low pressure sides of the device are. transposable, variable displacement means coactlng with the valvev plate, means forming a valve bore associated with the valve replenishing uid with the low kpressure side of the device. and the sleeve exposed to the high pressure side being movable relative to the stem to connect the high pressure side to the low pressure side through the last mentioned passage between the sleeve and stem upon attaining a predetermined pressure dierential between the high and low pressure sides.

15. A fluid power transmission comprising in combination a reversible and selectively variable duid displacement device including a valve plate having a pair' of uid passages withI respect to which the high and low pressure sides of the device are transposable, variable displacement means enacting with the valve plate, means forming a valve bore associated with the valve plate and communicating at its opposite ends with the respective passages, means forming a conduit between an intermediate point in the bore and a source of replenishing iiuid, the juncy tion of said conduit with the bore being oi limited extent axially of the bore in comparison to its extent transversely of the bore, and a shuttle valve slidably mounted in the bore, said shuttle valve including a longitudinal stem having headportions at its ends, a pair of sleeves slidably mounted on said stem, resilient means normally urging the sleeves outwardly against the heads, and means forming a fluid passage between the interior of. thesleeves and the stem normally closed by said head portions, said shuttle valve being movable to connect the source of replenishing iluid with the low pressure side o! the device, and the sleeve exposed to the high pressure side being movable relative to the stem. to

connect the high pressure side Ato the low pressure side through the last mentioned passage between the sleeve and stem upon attaining a predetermined pressure differential between the high and low pressure sides.

, EDWIN L. ROSE.

RALPH L. TWEEDALE. 

